Issue 085: Add indexer catch-up backfill tool with ledger range checkpoints

[orunganiekan]

Category: Backend
Complexity: 200 points
Labels: backend, wave-200

Context

Indexer resumes from meta last_ledger; replay-events.ts exists for audit.

Problem

Gaps after prolonged downtime need controlled backfill without duplicating or skipping ledgers.

Goal

Implement/harden backfill mode with start/end ledger, checkpointing, and rate limits compatible with RPC.

Scope

Includes: replay/backfill script UX + tests.
Does NOT include: archive node operations.

Implementation Guidelines

• Files: replay-events.ts, indexer.ts shared fetch helpers, query-events.ts.

Acceptance Criteria

• Checkpoint progressive
• Idempotent upserts
• Rate limit configurable

Validation

Backfill a small ledger range twice; row counts stable.

PR Expectations

The PR should include:

• Backfill mode + tests

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[abdulquadri123]

@abdulquadri123 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hey Maintainer,
As a blockchain developer, I will delighted to handle this issue and solve it diligently once assigned to me.
Thanks.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @abdulquadri123 to this issue.

[drips-wave]

Congratulations, @abdulquadri123! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on August 31, 2026.

🧑‍💻 @abdulquadri123: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

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